In response to the trend of the global energy depletion, people pay more attention to energy-saving; thus, people usually need to measure the electricity information of power cables so as to understand the electricity consumption information and save cost.
The most frequently-used power cable in the industry is three-phase three-wire power cable; if the user wants to use a power cable measurement device to measure the electricity information of the three-phase three-wire power cable of a machine in order to monitor the operation status of the machine, the user should turn off the power supply of the machine in advance; therefore, the machine cannot operate normally during the monitoring process.
Currently, many power cable measurement devices are developed to measure the electricity information of power cables. For example, U.S. Pat. No. 6,373,238 provides a three-phase electrical power measurement system for measuring the electricity information of a three-phase electrical power cable; US patent publication No. 20110074328 provides a whole structure contactless power consumption sensor for measuring the current and the power of a power cable; U.S. Pat. No. 9,007,077 provides a flexible current and voltage sensor for measuring the voltage and the current of a power cable; US patent publication No. 20050156587 provides a current sensor for measuring the current of a power cable. However, the above power cable measurement devices still have many shortcomings to be overcome.